Evaluation of polymerase chain reaction (PCR) for diagnosing Haemophilus influenzae b meningitis

Validation of multiplex PCR for the diagnosis of acute bacterial meningitis in culture negative cerebrospinal fluid

INTRODUCTION

This study evaluated the operational characteristics of the multiplex polymerase chain reaction (PCR) for cerebrospinal fluid (CSF) from patients with cellular and biochemical characteristics of acute bacterial meningitis and positive or negative CSF cultures.

METHODS

Multiplex PCR was performed for 36 CSF samples: culture-proven acute bacterial meningitis (n = 7), culture-negative acute bacterial meningitis (n = 17), lymphocytic meningitis (n = 8), and normal CSF (n = 4). The operational characteristics of multiplex PCR were evaluated with definite and probable bacterial meningitis, using culture positive, cytological and biochemical CSF characteristics as the gold standard.

RESULTS

Multiplex PCR for CSF was efficient in the group with CSF cellular and biochemical characteristics of acute bacterial meningitis but with a negative CSF culture. This group demonstrated high specificity, positive predictive value, and efficiency.

CONCLUSIONS

Multiplex PCR for CSF can improve the speed and accuracy of acute bacterial meningitis diagnosis in a clinical setting as a complement to classical immunological and bacteriological assays in CSF. It is also useful for CSF culture-negative acute bacterial meningitis.

16S rRNA Gene PCR/Sequencing of Cerebrospinal Fluid in the Diagnosis of Post-operative Meningitis

INTRODUCTION

Post-operative meningitis (POM) is a life-threatening complication of neurosurgery. Diagnosis is often difficult due to pre-existing inflammation and antecedent antimicrobial use. Bacterial cerebrospinal fluid (CSF) cultures may reveal no growth, but empiric antibiotics are typically given due to the high morbidity and mortality associated with POM. 16S rRNA gene PCR/sequencing is a molecular methodology that can identify the presence of bacteria regardless of viability for culture.

CASE PRESENTATION

A patient presented with a rapid onset of fever associated with headache, neck pain, nausea and altered mental status 11 days after undergoing laser interstitial thermal therapy for treatment of recurrent astrocytoma at another hospital. Based on clinical presentation and imaging, POM was suspected, and empiric antibacterial therapy was started. Microbiological stains and cultures of CSF were negative. Due to persistent fevers, 16S rRNA gene PCR/sequencing was done on CSF; it detected a member of the order Enterobacteriales most closely resembling Serratia species. All antimicrobials were stopped except for cefepime, which was given for 2 weeks. The patient's mental status fully recovered.

CONCLUSION

The application of 16S rRNA gene PCR/sequencing in the setting of POM is of value by improving the quality of patient care and decreasing costs by antimicrobial de-escalation. Further studies regarding the positive and negative predictive values of this test are required.

Principles of Management of Central Nervous System Infections

CNS infections in children are medical emergency and are associated with high mortality and morbidity. For diagnosis, a high index of suspicion is required. Clinical assessment should be supplemented by laboratory investigations including CSF Gram stain and cultures, blood culture, PCR on CSF, serological tests, and imaging. Commonly associated life threatening complications include coma, seizure, raised intracranial pressure (ICP), focal deficits, shock, respiratory failure, and fluid and electrolyte abnormalities. Immediate management should first address control of airway, breathing and circulation; protocolized management of raised ICP and status epilepticus; maintaining adequate intravascular volume; and close monitoring for early detection of complications. Appropriate antimicrobial agents should be administered promptly according to the suspected pathogen. Clinical evaluation, laboratory workup, specific antimicrobial therapy, supportive treatment, and management of associated complications should go hand in hand in a protocolized way for better outcome.

Incidence and aetiology of bacterial meningitis among children aged 1-59 months in South Asia: systematic review and meta-analysis

BACKGROUND

Bacterial meningitis is a significant cause of morbidity and mortality worldwide among children aged 1-59 months. We aimed to describe its burden in South Asia, focusing on vaccine-preventable aetiologies.

METHODS

We searched five databases for studies published from January 1, 1990, to April 25, 2017. We estimated incidence and aetiology-specific proportions using random-effects meta-analysis. In secondary analyses, we described vaccine impact and pneumococcal meningitis serotypes.

RESULTS

We included 48 articles cumulatively reporting 20,707 cases from 1987 to 2013. Mean annual incidence was 105 (95% confidence interval [CI], 53-173) cases per 100,000 children. On average, Haemophilus influenzae type b (Hib) accounted for 13% (95% CI, 8-19%) of cases, pneumococcus for 10% (95% CI, 6-15%), and meningococcus for 1% (95% CI, 0-2%). These meta-analyses had substantial between-study heterogeneity (I² > 78%, P < 0.0001). Among studies reporting only confirmed cases, these three bacteria caused a median of 78% cases (IQR, 50-87%). Hib meningitis incidence declined by 72-83% at sentinel hospitals in Pakistan and Bangladesh, respectively, within two years of implementing nationwide vaccination. On average, PCV10 covered 49% (95% CI, 39-58%), PCV13 covered 51% (95% CI, 40-61%), and PPSV23 covered 74% (95% CI, 67-80%) of pneumococcal meningitis serotypes. Lower PCV10 and PCV13 serotype coverage in Bangladesh was associated with higher prevalence of serotype 2, compared to India and Pakistan.

CONCLUSIONS

South Asia has relatively high incidence of bacterial meningitis among children aged 1-59 months, with vaccine-preventable bacteria causing a substantial proportion. These estimates are likely underestimates due to multiple epidemiological and microbiological factors. Further research on vaccine impact and distribution of pneumococcal serotypes will inform vaccine policymaking and implementation.

Acute bacterial meningitis in adults

Over the past several decades, the incidence of bacterial meningitis in children has decreased but there remains a significant burden of disease in adults, with a mortality of up to 30%. Although the pathogenesis of bacterial meningitis is not completely understood, knowledge of bacterial invasion and entry into the CNS is improving. Clinical features alone cannot determine whether meningitis is present and analysis of cerebrospinal fluid is essential for diagnosis. Newer technologies, such as multiplex PCR, and novel diagnostic platforms that incorporate proteomics and genetic sequencing, might help provide a quicker and more accurate diagnosis. Even with appropriate antimicrobial therapy, mortality is high and so attention has focused on adjunctive therapies; adjunctive corticosteroids are beneficial in certain circumstances. Any further improvements in outcome are likely to come from either modulation of the host response or novel approaches to therapy, rather than new antibiotics. Ultimately, the best hope to reduce the disease burden is with broadly protective vaccines.

The UK joint specialist societies guideline on the diagnosis and management of acute meningitis and meningococcal sepsis in immunocompetent adults

Bacterial meningitis and meningococcal sepsis are rare conditions with high case fatality rates. Early recognition and prompt treatment saves lives. In 1999 the British Infection Society produced a consensus statement for the management of immunocompetent adults with meningitis and meningococcal sepsis. Since 1999 there have been many changes. We therefore set out to produce revised guidelines which provide a standardised evidence-based approach to the management of acute community acquired meningitis and meningococcal sepsis in adults. A working party consisting of infectious diseases physicians, neurologists, acute physicians, intensivists, microbiologists, public health experts and patient group representatives was formed. Key questions were identified and the literature reviewed. All recommendations were graded and agreed upon by the working party. The guidelines, which for the first time include viral meningitis, are written in accordance with the AGREE 2 tool and recommendations graded according to the GRADE system. Main changes from the original statement include the indications for pre-hospital antibiotics, timing of the lumbar puncture and the indications for neuroimaging. The list of investigations has been updated and more emphasis is placed on molecular diagnosis. Approaches to both antibiotic and steroid therapy have been revised. Several recommendations have been given regarding the follow-up of patients.

Bacterial meningitis in children <2 years of age in a tertiary care hospital in South India: an assessment of clinical and laboratory features

OBJECTIVES

To assess the clinical and laboratory features of suspected meningitis to assist in the accurate diagnosis of bacterial meningitis in young Indian children.

STUDY DESIGN

Children <2 years of age with clinical suspicion of meningitis were enrolled. Clinical and laboratory information was collected, and cases were classified based on cerebrospinal fluid findings as clinical, aseptic, or probable and confirmed bacterial meningitis.

RESULTS

A total of 2564 children with suspected meningitis were enrolled over 45 months; 156 cases of aseptic and 51 cases of bacterial meningitis were identified. Stiff neck and bulging fontanelle were more common in bacterial meningitis (P < .05), but were present in <15% of patients. The World Health Organization and American Academy of Pediatrics classifications for high suspicion of bacterial meningitis were met in 84% and 88% of cases of bacterial meningitis, respectively, but were also present in 54% and 74% cases of aseptic meningitis. Culture and gram stain were positive in 7 (14%) and 4 (8%) cases of bacterial meningitis.

CONCLUSIONS

Signs of bacterial meningitis and proposed criteria for high suspicion of bacterial meningitis are non-specific in this population. Standard microbiological tests for bacteria are insensitive in this setting, necessitating highly sensitive methods to identify bacterial meningitis.

Acute respiratory infection and pneumonia in India: a systematic review of literature for advocacy and action: UNICEF-PHFI series on newborn and child health, India

BACKGROUND

Scaling up of evidence based management of childhood acute respiratory infection/pneumonia, is a public health priority in India, and necessitates robust literature review, for advocacy and action.

OBJECTIVE

To identify, synthesize and summarize current evidence to guide scaling up of management of childhood acute respiratory infection/pneumonia in India, and identify existing knowledge gaps.

METHODS

A set of ten questions pertaining to the management (prevention, treatment, and control) of childhood ARI/pneumonia was identified through a consultative process. A modified systematic review process developed a priori was used to identify, synthesize and summarize, research evidence and operational information, pertaining to the problem in India. Areas with limited or no evidence were identified as knowledge gaps.

RESULTS

Childhood ARI/pneumonia is a significant public health problem in India, although robust epidemiological data is not available on its incidence. Mortality due to pneumonia accounts for approximately one-fourth of the total deaths in under five children, in India. Pneumonia affects children irrespective of socioeconomic status; with higher risk among young infants, malnourished children, non-exclusively breastfed children and those with exposure to solid fuel use. There is lack of robust nation-wide data on etiology; bacteria (including Pneumococcus, H. influenzae, S. aureus and Gram negative bacilli), viruses (especially RSV) and Mycoplasma, are the common organisms identified. In-vitro resistance to cotrimoxazole is high. Wheezing is commonly associated with ARI/pneumonia in children, but difficult to appreciate without auscultation. The current WHO guidelines as modified by IndiaCLEN Task force on Penumonia (2010), are sufficient for case-management of childhood pneumonia. Other important interventions to prevent mortality are oxygen therapy for those with severe or very severe pneumonia and measles vaccination for all infants. There is insufficient evidence for protective or curative effect of vitamin A; zinc supplementation could be beneficial to prevent pneumonia, although it has no therapeutic benefit. There is insufficient evidence on potential effectiveness and cost-effectiveness of Hib and Pneumococcal vaccines on reduction of ARI specific mortality. Case-finding and community-based management are effective management strategies, but have low coverage in India due to policy and programmatic barriers. There is a significant gap in the utilization of existing services, provider practices as well as family practices in seeking care.

CONCLUSION

The systematic review summarizes current evidence on childhood ARI and pneumonia management and provides evidence to inform child health programs in India.

Meningococcal disease in Asia: an under-recognized public health burden

A literature search traced existing information on meningococcal disease in Asia. Reviewed data describing the epidemiology of meningococcal disease in Asia are incomplete, due in part to absence of surveillance in many countries, poor bacterial detection methods and social and healthcare barriers to disease reporting. This suggests that meningococcal disease in some Asian countries may be under-recognized, with a need to introduce/improve existing surveillance and case identification systems. Nevertheless, in some developing Asian countries, the disease burden may be significant. Serogroup A meningococcal epidemics are responsible for high morbidity and mortality in some countries and continue to be an ongoing threat, particularly in developing countries. There is an increasing role played by serogroups C, Y, and W-135 in invasive disease, indicating evolving meningococcal disease epidemiology in some countries. Multivalent meningococcal conjugate vaccines offer new opportunities in the region for reducing the meningococcal disease burden.

The epidemiology of meningococcal disease in India

OBJECTIVE

To undertake a review of the literature on the epidemiology of meningococcal disease in India, with a view to informing future control policies.

METHODS

We searched the PUBMED, EMBASE, Global Health, IMSEAR and MedIND databases for observational studies relating to the burden of endemic meningococcal disease in India, the occurrence and epidemiological characteristics of epidemics, and the prevalence of individual meningococcal serogroups.

RESULTS

The relatively few reports identified suggest that the incidence of endemic meningococcal disease in India is low, but that occasional epidemics of meningococcal disease have been recorded for at least 100 years. The larger epidemics have affected mainly the cities of northern India and have almost universally been caused by meningococci belonging to serogroup A. These epidemics have showed a few characteristics, including a marked seasonality, which are similar to those of epidemic meningococcal A disease in Africa.

CONCLUSIONS

New serogroup A-containing meningococcal conjugate vaccines are now being developed and reaching the market, including an affordable monovalent serogroup A vaccine manufactured in India, but intended primarily for use in Africa. These new tools may have a role in containing future Indian epidemics, but their usefulness is dependent on early identification of epidemics. This will require a functional disease surveillance system with adequate laboratory support throughout India.

A systematic review and critical evaluation of invasive Haemophilus influenzae type B disease burden studies in Asia from the last decade: lessons learned for invasive bacterial disease surveillance

In Asia, questions regarding the burden of Haemophilus influenzae type b (Hib) disease have delayed decision-making on introduction of Hib vaccine. However, over the past decade many studies have been published regarding Hib disease burden in Asia. We conducted a systematic literature review of all reports of Hib disease burden in Asia between 1998 and 2009, and critically reviewed their methods and data quality. We identified 94 studies from 28 countries in Asia presenting data on Hib disease burden. Of the 94 studies reviewed, 49 (52%) used a case definition consistent with World Health Organization standards, and 47 (50%) described laboratory methodology used. Twenty-seven surveillance studies presented data on incidence of Hib disease, with 8 (30%) accounting for missed cases, 6 (15%) accounting for cases with missed diagnostic tests, and 2 (7%) that considered prior antibiotic use. Of the 21 studies that provided incidence data for Hib meningitis, 10 (48%) used active, prospective, population-based surveillance, and found unadjusted incidence rates of Hib meningitis ranging from a low of 0.98 per 100,000 child-years in children aged less than 5 years in China to a high of 28 per 100,000 child-years in children less than 5 years in Mongolia. Of 49 studies that reported the etiology of bacterial meningitis, 30 (60%) identified Hib as the most common cause. This review highlights the importance of using rigorous methodologies, including standardized surveillance methods and appropriate laboratory diagnostic tests, when conducting studies measuring the burden of invasive bacterial diseases including those caused by Hib. When poorly conducted, studies can underestimate disease burden and lead to inappropriate decisions about vaccine introduction.

Bacterial meningitis: epidemiology, pathogenesis and management update

Bacterial meningitis continues to be an important disease throughout the world and can be a life-threatening emergency if not suspected, appropriately diagnosed and managed expeditiously. The epidemiology of bacterial meningitis has changed dramatically over the last 20 years, primarily as a result of the introduction of conjugate vaccines against the common meningeal pathogens, such that in the developed world where vaccination is routinely utilized, bacterial meningitis has become a disease of adults rather than of infants and children. The management approach to patients with suspected or proven bacterial meningitis includes emergent cerebrospinal fluid analysis and initiation of appropriate antimicrobial and adjunctive therapies. The choice of empirical antimicrobial therapy is based on the patient's age and underlying disease status; once the infecting pathogen is isolated, antimicrobial therapy can be modified for optimal treatment. Many patients with suspected or proven bacterial meningitis should also receive adjunctive dexamethasone therapy. This is based on experimental animal model data which demonstrated that the subarachnoid space inflammatory response that results from antimicrobial-induced bacterial lysis can contribute to morbidity and mortality. Clinical studies have demonstrated the benefit of adjunctive dexamethasone in infants and children with Haemophilus influenzae type B meningitis, and adults with pneumococcal meningitis, in which mortality and adverse outcome are reduced. Use of adjunctive dexamethasone in adults with meningitis caused by other bacteria, and in infants and children with pneumococcal meningitis, is controversial. To be effective, adjunctive dexamethasone should be administered concomitant with or just prior to the first antimicrobial dose for maximal effect on the subarachnoid space inflammatory response.

Incidence of bacterial meningitis in Asia using enhanced CSF testing: polymerase chain reaction, latex agglutination and culture

To enhance the detection of bacterial meningitis in an East Asian surveillance study, we employed cerebrospinal fluid (CSF) bacterial culture, latex agglutination (LA) and polymerase chain reaction-enzyme immunoassay (PCR-EIA) testing for Haemophilus influenzae type b (Hib) and Streptococcus pneumoniae (Sp). The sensitivity and specificity of CSF PCR-EIA testing was compared to LA and culture. A meningitis case was defined by one positive result for any of the three tests. The sensitivity of H. influenzae CSF PCR-EIA, LA, and culture was 100%, 40% and 57.5% respectively; and for Sp CSF PCR-EIA, LA and culture, the sensitivity was 100%, 58.3% and 66.7%, respectively. Hib and Sp specificity was 100% by each method. CSF PCR-EIA was more sensitive than culture or LA for the detection of Hib and Sp meningitis cases increasing their incidence by 74% and 50% compared to culture respectively. CSF PCR-EIA should be included for the detection of bacterial meningitis in surveillance studies.

Intensive care needs of children with acute bacterial meningitis: a developing country perspective

In view of very limited availability of paediatric intensive care (PIC) facilities in developing countries, it is important to define priorities and recognise children who might benefit most from PIC. The objective of this retrospective, descriptive analysis was to identify the clinical indicators for intensive care in children with acute bacterial meningitis (ABM). The study included 220 children aged between 1 month and 12 years with ABM admitted to the paediatric services of an urban, tertiary-care, teaching hospital in northern India from July 1993 to December 1996. Of these, 88 were transferred to the PICU by the primary physician, 59% were comatose (Glasgow coma score <8), 44% had raised intracranial pressure (ICP), 24% were in shock and 42% had respiratory distress/failure. Seizures occurred during their illness in 64 children, 34 of whom had refractory status epilepticus. Endotracheal intubation was needed in 29 and ventilatory support in 19 children. Most of the life support measures were required during the initial 48 hours. Nineteen (22%) children died, 16 of whom were comatose on admission. Multiple system involvement was associated with higher mortality. There were no deaths among the children who were not transferred to the PICU. Children with ABM who have a Glasgow coma score <8, clinical signs of raised ICP, refractory status epilepticus, shock and/or respiratory compromise should be prioritised to receive PIC.